On front wheel drive vehicles, the steering gear is mounted at the back of the engine compartment on the rear bulkhead. Space is limited in this region; and there are, therefore, packaging problems associated with the use of conventional power assisted steering gears in some vehicle models. Such gears have a valve for controlling hydraulic fluid flow arranged between the steering gear rack and the steering wheel as seen, for example, in Duffy U.S. Pat. No. 4,063,490, which is assigned to the assignee of this application. It is undesirable to locate the valve within the passenger compartment, and a conventional gear for such models, therefore, would project a long way into the engine compartment.
British Pat. No. 1,234,032 and U.S. Pat. No. 4,449,601 describe steering gears in which a rack and pinion is arranged between the valve and the steering wheel shaft. This results in a compact arrangement. However, it is considered necessary to provide torsional resistance to turning of the steering wheel to give steering "feel". In the gear disclosed in the British patent, tubular springs are provided in a special housing between the rack and pinion and the steering wheel. This arrangement has not proved satisfactory for production purposes since the characteristics of the springs used are not sufficiently uniform. Similarly, in the gear disclosed in the U.S. patent a C-spring is used to effect a steering "feel".